From the street, it looks like an ordinary house. Inside, though, is a small community of men and some women, mostly deportees, renting a warren of tiny rooms that filled in the home’s courtyard in makeshift fashion over the years.

After years of drug violence, Tijuana’s corridors were seedy places, home to drug addicts, and stinking with urine and rotting ceilings. But after the violence subsided, things started to change. Businesses found a new…